Field investigations of apparent optical properties of ice cover in Finnish and Estonian lakes in winter 2009

A field programme on light conditions in ice-covered lakes and optical properties of lake ice was performed in seven lakes of Finland and Estonia in February–April 2009. On the basis of irradiance measurements above and below ice, spectral reflectance and transmittance were determined for the ice sh...

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Bibliographic Details
Published in:Estonian journal of earth sciences 2011-01, Vol.60 (1), p.50-64
Main Authors: Lei, R, Leppäranta, M, Erm, A, Jaatinen, E, Pärn, O
Format: Article
Language:English
Subjects:
attenuation coefficient
lake ice
marin ekologi
Marine Ecology
optics
reflectance
snow
transmittance
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Summary:A field programme on light conditions in ice-covered lakes and optical properties of lake ice was performed in seven lakes of Finland and Estonia in February–April 2009. On the basis of irradiance measurements above and below ice, spectral reflectance and transmittance were determined for the ice sheet; time evolution of photosynthetically active radiation (PAR) transmittance was examined from irradiance recordings at several levels inside the ice sheet. Snow cover was the dominant factor for transmission of PAR into the lake water body. Reflectance was 0.74–0.92 in winter, going down to 0.18–0.22 in the melting season. The bulk attenuation coefficient of dry snow was 14–25 m –1 ; the level decreased as the spring was coming. The reflectance and bulk attenuation coefficient of snow-free ice were 0.1–0.4 and 1–5 m –1 . Both were considerably smaller than those of snow cover. Seasonal evolution of light transmission was mainly due to snow melting. Snow and ice cover not only depress the PAR level in a lake but also influence the spectral and directional distribution of light.
ISSN:1736-4728
1736-7557
1736-7557
DOI:10.3176/earth.2011.1.05